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6 Conditionals, loops, and recursion

Macros, expanding to plain text, perhaps with arguments, are not quite enough. We would like to have macros expand to different things, based on decisions taken at run-time. For that, we need some kind of conditionals. Also, we would like to have some kind of loop construct, so we could do something a number of times, or while some condition is true.

• Testing if a macro is defined
• If-else construct, or multibranch
• Recursion in m4
• Iteration by counting
• Iteration by list contents
• Working with definition stacks
• Building macros with macros